OVERVIEW
Radioactive heart damage refers to myocardial lesions produced by radiation exposure to radioactive substances. Radiation-exposed human and animal hearts have varying degrees of pathological changes, and the damaged areas include the pericardium, epicardium, endocardium, and even heart valves, as well as damage to the conduction system and coronary arteries, all of which are susceptible to radiologic heart damage.
Causes
1. Radiation therapy for malignant tumors, such as breast cancer, esophageal cancer, lung cancer, mediastinal tumors, Hodgkin’s disease and so on.
2. The dropping of atomic bombs in wars, the leakage of nuclear reactors, and the misuse of radioactive substances;
3. Radiofrequency or interventional therapy under X-ray irradiation for a long period of time with improper protection.
Symptoms
Acute reactions can develop in the patient’s heart within 24 hours of exposure, with delayed reactions occurring about 6 months or more after exposure. Acute damage to the heart in animal models occurs within 6 to 58 hours after irradiation, with delayed reactions occurring 2 to 3 months later. The manifestations of radiologic heart damage can be categorized into the following major types, and patients may experience one or more of these as the first symptom and throughout the main clinical course.
1. Pericarditis
There are two types of pericarditis: acute pericarditis and delayed pericarditis, which may also occur in the form of acute episodes of delayed pericarditis or recurrent pericarditis. The main clinical manifestations are fever, chest pain, fatigue and other symptoms. When the exudate is small, it may be asymptomatic or only mild shortness of breath after activity, while when the exudate is large, it may manifest progressive chest tightness, dyspnea and other symptoms of cardiac tamponade.
2. Myocardial fibrosis or total carditis
The latter includes pericardial fibrosis. Clinical manifestations are similar to constrictive pericarditis, with patients complaining of chest tightness, shortness of breath, and fatigue, accompanied by jugular venous distension and peripheral edema, and bruising of the liver, kidneys and other organs. This is mainly due to the large area of myocardial fibrosis, the heart’s contraction and diastole is limited, and this change mostly affects the right heart.
3. Asymptomatic cardiac decompensation
There are no obvious symptoms in several years or even decades after the patients receive radiation therapy, but the ejection fraction can be seen to have a tendency to decrease gradually after nuclear and echocardiographic follow-up, and selective right heart dysfunction can also appear; hemodynamic examination can find that the right ventricular pressure is elevated, and this change has nothing to do with age. It has been reported that the incidence of this type of myocardial damage can account for more than 50% of the follow-up patients, but due to the small impact on the patients, it has not been taken seriously.
4. Angina pectoris and myocardial infarction
This is a complication of coronary artery atherosclerosis and severe stenosis caused by radiation therapy. Clinical manifestations are the same as coronary artery disease, and repeated angina attacks can occur. These patients are often younger, usually no coronary heart disease factors, after radiation therapy only appeared myocardial ischemia performance, with the increase in age, the degree of ischemia can be significantly aggravated or accelerated development.
5. Electrocardiographic abnormalities
ST-T changes, bundle branch and atrioventricular block are common in this group of patients. Pre-phase systole may also occur, and there are individual reports of A.S. syndrome, which is a manifestation of radiation damage to the myocardium and the conduction system.
6. Valve function abnormality
Radiation therapy can cause valve thickening, but valve function abnormalities are rare. Sometimes, systolic murmur can be heard during auscultation, and echocardiography shows that the valve closure speed is slowed down. It generally occurs more frequently in the elderly than in the young and, like ECG abnormalities, tends to coexist with other manifestations. Cardiac symptoms in patients undergoing radiation therapy or exposed to high doses of radiation should be considered as the cause of radiologic heart damage, and even asymptomatic patients should be followed up and evaluated for cardiac function.
Examination
1. Chest X-ray
Enlarged heart shadow.
2.Electrocardiogram
ST-T changes, conduction abnormalities (atrioventricular or bundle branch block, etc.).
3. Echocardiogram
Enlarged heart shadow, liquid dark area can be seen when combined with pericarditis.
Diagnosis
Diagnosis can be made on the basis of etiology, clinical manifestations and laboratory tests. Radiation myocardial damage is often confused with various clinical cardiomyopathies, but patients with radiation heart damage often have received radiation therapy or have been exposed to high doses of radiation, which can be differentiated from other cardiomyopathies.
Complications
Radiation heart damage can be complicated by radiation pneumonitis, constrictive pericarditis, arrhythmia and other complications.
Treatment
Radiation therapy and those who are exposed to radiation should be actively protected, and those who have already suffered radiologic heart damage must be treated accordingly.
1. Pericarditis and myocarditis
Acute pericarditis is mainly treated with anti-inflammatory therapy. Because the inflammation is a kind of non-specific inflammation, so the first choice of hormone treatment, can be given to prednisone, oral; or dexamethasone, oral; exudate more pericardial puncture decompression can be injected into the pericardial cavity hydrocortisone, can achieve better results.
The treatment principle of chronic pericarditis is still controversial: because it is not easy to determine the degree of involvement of myocardial fibrosis in patients with constrictive pericarditis after repeated pericardial exudation, about half of the patients after pericardial dissection did not significantly improve their symptoms, therefore, many clinicians are still mainly to take the diuretic, vasodilatation, decompression and other conservative treatments for chronic pericarditis, and if the condition is basically stabilized, they will no longer consider further surgical treatment! If the condition is basically stabilized, no further surgical treatment will be considered, and pericardial dissection will be performed only when progressive dyspnea, persistent hepatomegaly, pleural effusion, and ineffective drug treatment occur. The treatment principle of myocarditis is basically the same as above.
2. Coronary artery lesions
After radiotherapy, attention should be paid to the adjustment of diet, blood pressure and blood sugar control, and percutaneous transluminal coronary angioplasty (PTCA) or bypass grafting can be carried out for serious stenosis of coronary arteries that have been formed. For angina pectoris or myocardial infarction, it should be treated according to the corresponding diagnosis and treatment routine.
3. Arrhythmia
For severe three-branch block or high atrioventricular block and other severe damage to the conduction system, pacemakers can be installed. A small number of high-risk pre-systolic contractions should be actively handled, and antiarrhythmic drugs with fewer side effects can be used when the symptoms are obvious, such as mesylate, atenolol (amylase), etc. Measures to protect and nourish the myocardium can be taken for patients with persistent ST-T changes.
4. Discomfort caused by radiation therapy
Before and after irradiation, the patient can take teicoplanin or fenaijing orally; after radiation therapy, the patient can take traditional Chinese medicines which can replenish qi, blood and kidney yang to regulate the body, such as Astragalus, Codonopsis pilosulae, Radix Rehmanniae Praeparata, Radix Angelicae Sinensis, Radix Rehmanniae Praeparatae, Radix Polygoni Multiflori, Radix Astragali, Radix Codonopsis pilosulae, Radix Rehmanniae Praeparatae, Radix Rehmanniae Serratae, Radix Polygoni Multiflori, Radix Cistanchiae and so on. This may help to improve the patient’s own immunity and reduce the toxic side effects.